Dean Foods and Thermo King are working together on a prototype all-electric refrigeration system, the companies have announced. The unit, placed into service in March, is being tested at Dean Food’s Dallas-area facility.

Based on Thermo King’s TS500 model, the unit is powered through the truck’s alternator using power generated by the engine to supply electrical power. When the vehicle is not running, the unit can be plugged into shore power through a commercial 230-volt outlet. If the truck is turned off and the system is not plugged in to shore power, it does not run.

There is no independent engine for the refrigeration unit, meaning there is also no oil, filters or anti-freeze to maintain. They also emit less noise than mechanical refrigeration systems.

“Results have been very promising so far,” said Mike Ahart, vp of transportation. “While this is one of a kind, Thermo King is working diligently towards perfecting this prototype before making the jump into full production. We have a very large fleet of vehicles and it is certainly possible that some day this may be the only refrigeration system we use.”

Thermo King says it hopes to have production-ready versions of the system by next year.

Dean Foods is in the process of converting its entire truck fleet – a mix of International 4300 and Freightliner M2 models fitted with Johnson refrigerated bodies - over to cold-plate technology, a process started in 2007.

The company has set goals to reduce its carbon footprint by 20%, water use by 30% and solid waste by 30%, all by 2013, as part of its Environmental Roadmap initiative.

“Our highest priority is reducing the cost and improving the efficiency of our operations,” said Harrald Kroeker, president of Dean Foods’ Fresh Dairy Direct business unit. “Innovations that eliminate the use of diesel fuel, which is a major expenditure and our second largest source of emissions, drive cost savings to our business that benefits the environment.”

If fully implemented, the refrigeration system would provide a 50% savings in diesel fuel usage and remove 21,000 lbs. of carbon per vehicle, per year, the company said. Dean Foods has a goal of removing 50,000 metric tons of carbon from its transportation system by 2013.

“The truck engine supplies power to a generator that produces 9 kW of electricity at idle and just over 17 kW at maximum rpm,” said Ahart. “This produces sufficient electricity to allow the refrigeration unit to operate normally even as the truck idles, such as at a stoplight. There is no storage of electricity to any significant extent.”